Complex Size and Surface Charge Determine Nucleic Acid Transfer by Fusogenic Liposomes

Abstract

Highly efficient, biocompatible, and fast nucleic acid delivery methods are essential for biomedical applications and research. At present, two main strategies are used to this end. In non-viral transfection liposome- or polymer-based formulations are used to transfer cargo into cells via endocytosis, whereas viral carriers enable direct nucleic acid delivery into the cell cytoplasm. Here, we introduce a new generation of liposomes for nucleic acid delivery, which immediately fuse with the cellular plasma membrane upon contact to transfer the functional nucleic acid directly into the cell cytoplasm. For maximum fusion efficiency combined with high cargo transfer, nucleic acids had to be complexed and partially neutralized before incorporation into fusogenic liposomes. Among the various neutralization agents tested, small, linear, and positively charged polymers yielded the best complex properties. Systematic variation of liposomal composition and nucleic acid complexation identified surface charge as well as particle size as essential parameters for cargo-liposome interaction and subsequent fusion induction. Optimized protocols were tested for the efficient transfer of different kinds of nucleic acids like plasmid DNA, messenger RNA, and short-interfering RNA into various mammalian cells in culture and into primary tissues.

Non-viral vectors for RNA delivery

“…For example, some researchers combined fusogenic lipids (DMPC) with solid porous silicon nanoparticles (pSiNP) cores, loaded siRNA into pSiNPs via calcium ion precipitation, and showed that the uptake mechanism could be engineered to be independent of common receptor-mediated endocytosis pathways [ 170 ]. Marco et al [ 171 ] also analyzed the composition and proportion of lipids and concluded that factors such as surface charge and particle size would affect the occurrence of membrane fusion, thus affecting the transfer of various nucleic acids. Since most membrane fusion is mainly a process driven by physicochemical properties of particles and plasm membrane, the fusion efficiency is basically irrelevant to cell types.…”

Research Progress on Nanoparticles-Based CRISPR/Cas9 System for Targeted Therapy of Tumors

“…Therefore, liposomes as three-dimensional spherical structures that encapsulate hydrophilic or hydrophobic molecules can enter cells by endocytosis [ 70 ]. When a liposome is positively charged, DNA and RNA can form strong bonds through electrostatic attraction, adsorbing them on the surface of liposome [ 71 ], which efficiently protects the nucleic acid from degradation. Currently, commercial cationic liposomes and lipofection kits are available for the delivery of RNAi gene and plasmid DNA (pDNA).…”

Liposome Assisted Drug Delivery-An Updated Review

“…Elsewhere, Fusogenic Liposomes (FLs) were prepared by fusing conventional liposomes with inactivated viruses. FLs delivered the content directly to the cytoplasm without the drawback of cytotoxicity, hence emerged as a powerful tool for gene delivery systems [111,112] . However, it is recently shown that NATs have set foot in clinical applications after overcoming limitations of limited cellular uptake, low biological stability and offtarget effect.…”